1. Technical Field
The invention relates to a plastic container with a snap lid and with a snap element provided on the upper edge area of the container for the lid to snap onto, where the lid surrounds the top and outside of the container edge and sits tight against the container edge.
2. Prior Art
Plastic containers of this kind are used to transport various goods, particularly also in the industrial and food sectors, and have proven to be very effective for this purpose. However, transporting liquids or low-viscosity materials still involves the problem of the sufficient leak-proofness of the plastic containers, particularly also when transporting volatile or other types of critical goods, such as oils or mineral oils, where this leak-proofness should reliably be maintained, especially also in the event of external effects, such as blows or jolts, or of the plastic container falling. These high demands have not yet been fulfilled satisfactorily by previously known plastic containers, meaning that critical goods are still usually transported in metal containers.
An object of the invention is to provide a plastic container with snap lid, which reliably fulfills the special demands imposed on leak-proofness, particularly when exposed to external forces.
The object is solved by a plastic container with snap lid, in which the container edge on the side of the snap element facing the top edge of the container is provided with at least one integrally moulded reinforcing rib projecting radially inward and/or outward and extending over at least a segment of the circumference of the container. The reinforcing rib is thus located between the snap element and the top edge of the container. The reinforcing rib can be provided on the side of the container opposite the snap element, but is advantageously located on the same side. The snap element and the reinforcing rib are advantageously located on the outside of the container and engaged from above by the lid. The reinforcing rib further stabilises the top edge of the container and thus the sealing region between the container and the lid. In this context, the xe2x80x9creinforcing ribxe2x80x9d is taken to mean a rib that is provided in addition to a snap projection and thus not associated with a corresponding snap edge of the lid.
The reinforcing rib preferably runs radially around the container, although it can also be divided and consist of several, e.g. segmented reinforcing areas that are distributed around the circumference. One or more additional reinforcing ribs, which can each run radially around the container, can alternatively or additionally be integrally moulded on the side of the snap element facing towards, or also away from, the top edge of the container. The thickness, i.e. height and/or width of the reinforcing rib can be in the region of half the wall thickness of the container, preferably in the region of the wall thickness or greater than it. If necessary, it can also be less than half the wall thickness, particularly if the rib is structured, as long as it significantly reinforces the upper region of the container.
The lid preferably sits on the radially outer or inner side of the reinforcing rib with or without pretension, so that lateral forces acting on the lid are immediately absorbed by the reinforcing rib. To this end, the radial edge of the reinforcing rib can have a plane area. The distance between the reinforcing rib and the snap element, or between them, can be designed to catch the snap edge of the lid, so that the lid can be pre-locked on the container.
Advantageously, the snap connection of the lid is also equally effective after the container has been opened once, i.e. the snap region and the sealing region are not separated by an area of thinner material, which serves as a tamper-proof seal, for example, and in which the lid area has to be partially or completely removed or folded over in order to open the container.
The upper edge of the container preferably has a circumferential collar region projecting radially outward and facing downward, on which a tamper-proof seal can be provided, for example. The circumferential collar region is preferably radially flush with the height of the lid rim, or projects radially beyond it. The snap edge is preferably integrally moulded on the circumferential collar. A reinforcing rib integrally moulded above the snap element and preferably facing outward can also be integrally moulded on the circumferential container collar, thus also reinforcing it, and/or above the circumferential collar region right on the container wall in the region of the top edge of the container. Due to the downward-facing collar region, which is spaced apart from the container wall, the snap region is isolated from the sealing region in terms of the forces acting on them. The reinforcing rib is preferably integrally moulded on the top edge of the circumferential collar, or on the container wall, right on the top edge of the container, without being restricted to this. For example, the reinforcing rib can also be located a small distance away from the top edge of the circumferential collar or the container collar, e.g. at distance of one or a few times the wall thickness or the thickness of the reinforcing rib.
The snap element and the reinforcing rib can also be integrally moulded on the container wall above the circumferential collar.
The downward-facing, circumferential collar region is preferably joined at the top edge of the container, i.e. at the height of the sealing region or at a distance of a few times the wall thickness away from it, e.g. one or two times the wall thickness, without being restricted to this.
The lid preferably has an outwardly-facing sliding bevel, which can be joined to the top edge of the lid or a region below it, preferably on an essentially vertical section. The sliding bevel can be located immediately above the reinforcing rib provided above the snap element on the outer wall of the container and a small distance away from it. The sliding bevel can be radially flush with the snap edge of the lid on the outside, or extend beyond it, although it preferably extends radially beyond the areas projecting away from the container wall.
The container preferably has a collar region projecting radially outward and facing downward, which is located below the lid when it is on the container and extends radially to the lid or also beyond it. This circumferential collar region can be integrally moulded on the container wall separately and, in this context, be flush with the bottom edge of the circumferential collar region with the snap edge, or spaced apart from it in terms of height. This circumferential collar region is preferably designed as a continuation of the collar region accommodating the snap element, i.e. as a shoulder continuing down and to the outside. A corresponding tamper-proof seal can be provided in this area. The bottom edge of the lid can sit on this collar region with or without pretension, or display a slight amount of play in relation to it, preferably such that the bottom edge of the lid cannot be reached under manually. This circumferential collar region can have a radial constriction for the partial or complete reception of the bottom edge of the lid.
The circumferential collar region or regions can be reinforced by vertical ribs, which can be mounted in the inside of the collar region and connected to the outer wall of the container. The reinforcing ribs preferably have a recess or notch at the bottom, due to which the collar region retains a certain degree of flexibility and can act as a deformation zone.
The sealing region between the container and the lid is preferably provided with a circumferential and possibly separate seal that sits tightly between the container and the lid when the lid is in place, where the seal is made of a material of greater elasticity than that of the lid and the bucket, particularly a rubber material.
It is particularly preferable for the flexible seal to be integrally moulded on the container and/or lid. This makes it possible to avoid the tolerances that can occur with the alternative possibility of providing a manually inserted seal, and the seal is also always located on the component in unmoveable fashion, even when exposed to external forces, e.g. if containers fall. The seal is preferably integrally moulded by an injection process, e.g. injection moulding, so that joints or the like can be avoided. The seal can be injected in the same mould immediately after the moulding of the associated container part, so that low manufacturing and fit tolerances, in particular, can be maintained.
The seal is advantageously integrally moulded on the lid. The seal can have an essentially horizontal sealing region and it can also be profiled, e.g. U or V-shaped. One, two or even more different sealing regions can be provided that differ in terms of their contact width, which can be either linear or planar, material thickness or other characteristics. The sealing regions can be interconnected and/or radially or axially separated from one another.
As a result of the arrangement of the reinforcing rib next to the flexible seal, the sealing region of the container is particularly stabilised.
The seal is advantageously located in a circumferential groove in the lid that is open towards the container edge, where the seal can extend over the entire width of the groove and is thus additionally secured against lateral shifting. The side flanks of the groove can surround the inside or outside of the container edge, preferably with slight lateral play, or none at all, without being restricted to this.
The seal preferably has two, adjacent sealing regions that are at different angles and tightly contact areas of the container edge at different angles. To this end, the seal can have a U, V or L-shaped cross-section, in particular, or other profiles, where the sealing regions can be arranged on opposite areas of the seal, possibly also in a convex area, for example.
When the container is closed, the seal preferably has an essentially horizontal area that tightly contacts the top edge of the container and a radially inward area that preferably slopes downwards and tightly contacts the inside of the upper container edge. The downwardly sloping sealing region can extend essentially vertically or at an angle when the container is in upright position, where the two sealing regions can enclose an angle of 90xc2x0 to 135xc2x0 or more. The container edge preferably likewise has a horizontal sealing region and a radially inward bevel or chamfer for positioning the vertical or angled sealing region. However, other designs are also possible. As a result, forces are always absorbed in the region of the flexible seal, even forces acting laterally on the sealing region, so that a high degree of leak-proofness is ensured.
The sealing region can have one or more circumferential sealing ribs projecting towards the container edge, which tightly contact the corresponding component, e.g. the container, particularly the top edge of the container. The sealing rib can be provided when using a flexible seal, as well as when the sealing region is created by a contact area between the container and the lid, e.g. is made of the same material as these components, or possibly also of some other material that need not have greater flexibility than these components. The contact area is preferably plane. It can extend horizontally and, for example, form the top edge of the container.
Regardless of the material selected, the height of the sealing rib is preferably less than the wall thickness of the adjacent component, e.g. the container, preferably less than xc2xd or ⅕ the container wall thickness or smaller, without being restricted to this. Particularly if the sealing rib is made of a material with a stiffness roughly equal to that of the container material, the sealing rib can also be of greater height.
The width of the sealing region, i.e. its radial extension, can be greater than the wall thickness of the upper container edge, e.g. approximately 1.5 to 3 times greater, without being restricted to this. This applies to flexible seals as well as to sealing regions without greater flexibility.
The container edge can be plane or provided with one or more circumferential ribs, pairs of which can form a groove that is at least partially engaged by one or more sealing ribs. The sealing ribs can be provided on different areas of the seal, e.g. on a horizontal and/or vertical or angled area. The cross-sections of the sealing ribs need not be the same as the circumferential grooves of the container edge, as long as a sufficient sealing effect is achieved. The cross-section of the groove of the container edge can be equal to or smaller than the cross-section of the sealing rib, so that the groove is completely filled by the flexible sealing rib when the lid is in place. The groove cross-section can also be larger than that of the engaging sealing ribs and, in this context, counteract the lateral shifting of the same, for example, a purpose that can also be fulfilled by just a web. The web or edge delimiting the groove can also tightly contact the seal. If necessary, one or more ribs can also be provided on the container edge that engage recesses provided specifically for this purpose in the flexible seal. In particular, the seal and container edge structures that come into contact, which can differ in terms of height and/or width, for example, can be incompatible or non-complementary, so that elevations on the seal do not lie opposite depressions in the container edge, but rather contact elevations on the container edge, e.g. in the flank area of the same. This results in non-congruent interlocking that ensures high and reliable leak-proofness. If the sealing rib is made of a material of sufficient stiffness, e.g. the container material, the sealing rib is accommodated by a preferably congruent groove, in which the sealing rib can also be located in a press fit.
The seal preferably has a height or thickness such that it simultaneously acts as a deformation zone when force is exerted on the container or the lid in the sealing region, so that deformation of the more rigid lid and container areas can be avoided when exposed to certain forces.
Webs projecting radially outward, which can be designed as circumferential ribs whose radial extension is less than the container wall thickness, can be integrally moulded on the outwardly downward-sloping area of the outer container wall adjacent to the top edge of the container. These ribs can be made of the same material as the container wall and essentially serve to reduce the friction when putting on the lid, where they only have a secondary sealing function, which is primarily fulfilled by the flexible and compressible seal. Two or more circumferential ribs of this kind can also be provided on the outer edge of the container. When the lid is in place, the ribs preferably make contact without play, but also without any significant pretension, so that the lid is precisely positioned in the region of the seal, or are spaced apart with slight play, without being restricted to this.
The lid preferably has a circumferential area that is spaced vertically and/or radially away from a possibly provided flexible seal and tightly contacts the inside wall of the container when the lid is in place. This sealing region can be made of the same material as the lid. The sealing region can be designed as a downwardly projecting rib or also as a shoulder on the underside of the lid, for example, and is preferably located above an indentation in the container wall when the lid is in place. When the lid is in place, the sealing region can rest on the indentation, or be spaced away from it, preferably in such a way that the underside of the rib or of the shoulder of the lid rests on the container indentation when additional containers are stacked on top or when an external force is applied. In this context, the lid area can tightly contact a preferably essentially vertical container region in linear fashion, or over a vertical height, preferably at the height of a reinforcing rib or the snap edge provided on the outside of the container.
The reinforcing rib is preferably located at least roughly at the height of an area of the lid that directly contacts the inside wall of the container. The lid area is preferably designed as a circumferential sealing region. The vertical distance of the rib from the contact area of the lid on the inside wall of the container can be in the region of 0 to 5 times the container wall thickness, such as in the region of roughly 1 to 2 times the container wall thickness, without being restricted to this. In this context, the reinforcing rib can be provided above, below or exactly level with the contact area between the lid and the inside wall of the container.
In order to increase the reliability of the container seal, an area projecting upward beyond the bottom edge of the rib can be provided on the inside wall of the container, which is radially inside relative to the web-like or circumferential rib integrally moulded on the inside of the lid. To this end, individual projections or webs can provided that are spread over the circumference. This area is preferably also designed as a circumferential rib. The height of this rib, which prevents inward shifting of the rib of the lid, is preferably smaller than the wall thickness of the container or the lid rib, without being restricted to this. The upwardly projecting areas of the container can be slightly spaced apart or contact the side of the rib of the lid with or without pretension. In this context, the rib of the lid can also be located in a press fit between the radially adjacent container areas on the inside and outside.
The shoulder of the inside wall of the container, which is located below the rib or a shoulder of the lid or the like, can be located roughly at the height of the snap element or a reinforcing rib, or at distance of one or a few times the wall thickness of the container.
In order to stabilise the sealing region, the lid can be provided, preferably on the immediately radially inside area of the container wall, with at least one radially inward projection that can be integrally moulded on the top side of the lid. The projection or projections can be of annular, box-like (e.g. cubic or prismatic) or web-shaped design, without being restricted to this. Inside reinforcing ribs can be provided in order to stabilise the box-like or annular projections.
The top side of the projection(s) is advantageously spaced away from, preferably above, the lid area in tight contact with the inside wall of the container, where the point of contact in the vertical direction can be virtually punctiform or linear. The cross-section of the projections can be designed in the shape of a skew triangle or rectangle, where the top and/or bottom edge of the side walls of the projections can be designed to slope down towards the inside of the container. The radially inward end wall of the projections can be vertical or at an angle. The projections can be integrally moulded on the top edge of the lid. The top edge of the projections is preferably located below the top edge of the lid, thus creating another shoulder. This avoids integral moulding at the height of the sealing region on the inside of the container, which can lead to material stress or deformation, e.g. due to shrinkage processes.
The projections facing the centre of the lid are advantageously designed such that vertically extending connecting surfaces with the circumferential sealing rib can be largely or entirely avoided in the sealing region, such as in the form of lateral surfaces on the projections or web-like projections. To this end, projections extending over a relatively large part of the circumference, or preferably a radial circumferential edge on the inside of the lid, can be provided. In this context, the lateral surfaces of the projections can be located at a radial distance from the circumferential sealing region on the top side of the projections, so that when looking at the lid from below, a circumferential groove with an e.g. roughly trapezoidal or triangular cross-section and inwardly facing wider areas results. The projections, particularly also an annular, circumferential projection, can possibly also be reinforced with inside ribs, which then preferably end at a radial distance from the sealing or support rib in contact with the inside wall of the container, or rest against it at a distance from the sealing region of this rib.
In this context, the top side of the projections can contact the inside edge of the lid essentially horizontally, preferably at a downward angle of less than 15xc2x0, e.g. 5xc2x0, towards the inside of the container.
The lid surface blocking the container opening can be positioned level with or below the inside sealing region, preferably level with or below the snap edge.